There is little scientific dispute at this point that global warming is occurring, and that humans are causing some part of it, as even the Competitive Enterprise Institute (a conservative free enterprise think tank) is now willing to admit. The remaining question: just how big a problem is global warming, and what are the consequences if we do nothing? An Inconvenient Truth makes it appear that Florida will be underwater sometime soon if we sit idly by. Reality, at least as scientists currently understand it, probably lies somewhere between Al Gore’s doom-saying and CEI’s laughable slogan, “CO2: We Call It Life.”

Of all the potential effects of global warming, rising sea levels are thought to have the most catastrophic consequences. If the Greenland ice sheet or a large part of Antarctica really do melt, the resulting 20 foot rise in sea levels would destroy the majority of the world’s great cities and displace billions of people. But how long will a rise of 20 feet, or even two feet, take at current rates of warming and ice melt? Realclimate.org summarizes recent research here, wherein the most aggressive estimates indicate that Greenland’s ice sheet melting is increasing sea levels by up to 0.57mm per year. But if Greenland continues melting at that rate, it will take one thousand years to raise sea levels one foot!

Even an order of magnitude increase in ice melting would only cause sea levels to rise a foot by 2100. The Intergovernmental Panel on Climate Change Report’s most aggressive estimate calls for a three foot sea level rise by 2100; this estimate includes significant ice melt. While this scenario has significant implications for coastal cities, it is not apocalyptic, and it also represents an outlier prediction compared to most climate models. It seems then that we should care about global warming in the very long term, but it is unlikely to have a significant impact during our lifetime. There are dozens of environmental and social issues that deserve greater present concern, including the AIDS pandemic and infectious diseases like tuberculosis and malaria, which continue to kill tens of millions annually.

At the same time, it wouldn’t hurt to take some simple steps to curb CO2 emissions growth. The CEI and others complain that it is impossible to curb CO2 emissions growth without hurting the economy. On the contrary, prudent shifts in government policy can reduce emissions while increasing growth. If the United States were to fund all highway construction with gasoline taxes, for instance, this would pass the costs of car travel directly on to the end consumer – which increases economic efficiency while decreasing emissions. I’ve written previously about applying the gas guzzler tax fairly, so that consumers are not rewarded for buying large SUVs instead of large cars. Finally, ending the huge subsidies to the oil, gas, and coal industries would make alternative energy more competitive, while saving taxpayers billions.